1. Field of the Invention
This invention relates to a semiconductor fabrication facility and, more specifically, to such a facility which requires reduced clean room area, less cumbersome working conditions for the operators and reduced ultimate fabrication costs.
2. Brief Description of the Prior Art
Semiconductor fabrication facilities generally require that all process steps wherein the semiconductor wafer can be exposed to external contaminants be conducted in a "clean" atmosphere to avoid or at least minimize the likelihood that such contaminants ultimately reside on the wafer itself The degree of cleanliness required has become more acute as the dimensions of the components on the wafer decreased with time because this decrease in dimensions enables continually smaller contaminants to be capable of causing irreparable damage to the semiconductor devices being fabricated. In order to provide the required degree of cleanliness, it has been necessary to enclose the processing equipment in "clean" rooms with the degree of cleanliness being required to meet certain specified standards as is well known in the art. The fabrication tools are located throughout the "clean" room and operators wearing special garments are required to transport batches of semiconductor wafers from fabrication tool to fabrication tool within the "clean" rooms up to encapsulation of the device at which time the device can be removed from the "clean" room since it is no longer subject to possible contamination. Each fabrication tool has its own support skid attached thereto which includes items such as RF power supplies, vacuum pumps, gas cylinders, etc. These clean rooms require specified air circulation and filtering as well as zones above and below the "clean" room floor and ceiling for additional cleanliness protection, this requiring essentially three floors. Also, the personnel within the clean room are required to wear special gowns to further avoid introduction of contaminants into the "clean" room. These requirements include the use of a great deal of space for the equipment and operators, provide cumbersome working conditions for the operators in that special garments must be worn and require significant cost to maintain the large "clean" room ambient volume at the required level of cleanliness. Typical prior art semiconductor fabrication facilities are discussed in the U.S. Pat. No. 5,344,365.